1. Field of the Invention
The present invention relates to a heat generating element, particularly for an electrical heating device of a motor vehicle, having a positional frame, which forms a receptacle in which at least one PTC element is accommodated, and contact plates abutting on two oppositely situated sides of the PTC element.
In particular, the present invention relates to a heat generating element of an electrical heating device for a motor vehicle, whereby the heating device has a frame which, on opposite sides, forms openings for the passage of a medium to be heated. Arranged in the frame is a layer structure that accommodates the aforementioned heat generating element, whereby in the layer structure, in each case corrugated-rib elements abut normally on oppositely situated sides of the heat generating element in a manner that conducts heat in order to discharge regularly the heat generated by the heat generating element to the medium that is to be heated, which medium usually is air.
2. Description of the Related Art
An electrical heating device of this nature is for example known from DE 199 11 547, U.S. Pat. No. 5,854,471, EP 0 350 528 or DE 197 06 199.
EP 1 768 457 A1, which originates with the applicant, can be seen as type-defining for the heat generating element that forms the object of the present invention. In this state of the art, the receptacle formed by the positional frame has on its inner circumference a spacing element which bridges an insulating gap that is to be provided between the plastic material of the positional frame and the PTC element.
By means of this, a highly insulating support of the PTC element in the positional frame formed from a plastic material that is unspecific with regard to its electrical conductivity is to be improved. According to this state of the art, the insulating support element is formed from a silicon strip that is attached to the inner circumferential surface of the positional frame by means of a tongue and groove joint.
This previously known suggested solution is relatively elaborate because the silicone strip must be joined to the plastic material of the positional frame at a later time. The same applies to the parallel suggested solution according to EP 1 768 458 A1.
For example, EP 1 768 457 A1 and EP 1 768 458 A1 each disclose solutions for heat generating elements that should be suitable for high voltage use. The solutions presented there are, however, seen as in need of improvement with respect to an insulating support of the PTC element in the positional frame.